don't allow TestLatency to run when MOZ_IPC_MESSAGE_LOG is set

ipc/ipdl/test/cxx/TestLatency.cpp

@@ -36,6 +36,9 @@ TestLatencyParent::~TestLatencyParent()
 void
 TestLatencyParent::Main()
 {
+    if (mozilla::ipc::LoggingEnabled())
+        NS_RUNTIMEABORT("you really don't want to log all IPC messages during this test, trust me");
+
     PingPongTrial();
 }